1. Field of the Invention
The invention relates to a power supply apparatus, and more particularly, to a power supply apparatus having multiple connecting ports and an operation method thereof.
2. Description of Related Art
In general, when the power supply apparatus supplies power to charge an electronic apparatus, the power supply apparatus needs to perform a voltage conversion operation according to a charging specification of the electronic apparatus so an output voltage of the power supply apparatus can satisfy a demanded voltage of the electronic apparatus. The power supply apparatus may include a plurality of connecting ports for supplying power to different electronic apparatuses at the same time. The power supply apparatus has a plurality of voltage converters to respectively provide different output voltages for different connecting ports, and different electronic apparatuses may be respectively connected to these connecting ports to receive these output voltages.
The voltage converters of the power supply apparatus commonly use one fixed source voltage to generate different output voltages separately. A level of the fixed source voltage does not change with changes in voltage demands of the connecting ports. Usually, the level of the fixed source voltage needs to be very high in order to satisfy high voltage demands of the connecting ports. For instance, if the voltage demands of the connecting ports fall within a range of 5V to 20V, the level of the fixed source voltage may be 24V. When the voltage demand of one connecting port is 20V, the voltage converter can convert the fixed source voltage (i.e., 24V) into an output voltage (i.e., 20V). However, when the voltage demand of one connecting port is 5V, the voltage converter needs to pull the voltage from 24V down to 5V. Normally, a voltage conversion efficiency of the voltage converter is lower if the voltage drop is greater. When the voltage converter pulls the voltage from 24V down to 5V, the voltage conversion efficiency of the voltage converter would be reduced such that a part of power not being converted would be lost in form of heat. Consequently, the charger may suffer an overheat condition.
Therefore, it is necessary to provide a new power supply apparatus to solve the problem caused by poor voltage conversion efficiency of the conventional power supply apparatus.